The invention relates generally to the preparation of tube end portions for welding together, and particularly to an apparatus that will conveniently prepare the tube portions for welding in a manner that insures a high quality weld for multiple draw purposes, though the invention is not limited thereto.
In U.S. Pat. No. 3,765,215 to Martin there is shown a method and apparatus for drawing tubular stock continuously and simultaneously through at least two successive drawing dies having mandrels located within the stock being drawn. Individual successive capstans are employed to direct the stock to the respective dies and to pull the same from the dies. With such a process and apparatus, simultaneous reduction of the cross sectional area of the stock is effected with a single pass of the stock through the dies and around the capstans.
In U.S. Pat. No. 3,912,151 to Martin et al there is shown a method and apparatus for welding the ends of tubular stock together for the purpose of providing a continuous length of stock for the drawing process described in the first Martin patent. In the second, Martin et al patent the ends are welded together along an interface that is angled, with respect to the axis of the stock, to provide an angular weld that will withstand the severe conditions encountered in the multiple draw process of the first Martin patent. The conditions are severe because the tube and welds are continuously being wrapped around the capstans and pulled from the capstans through the dies at substantial speed such that the forces on the welds are quite severe. The angled weld of the second Martin el al patent provides overlapping portions of the welded tube ends to receive the bending forces exerted by the successive capstans in a gradual manner and to enter the successive dies in a gradual manner thereby avoiding the shock of the complete weld entering the die at one instant of time.